#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int main()
{
	int i;
	int sign = 1;
	double sum = 0;
	for (i = 1;i <= 100;i++)
	{
		sum += 1.0 / i*sign;
		sign = -sign;
	}
	printf("%f",sum);
	return 0;
}